Institute of Applied Acoustics, Shaanxi Normal University, Xian, Shaanxi, PR China.
IEEE Trans Ultrason Ferroelectr Freq Control. 2012 Jan;59(1):139-49. doi: 10.1109/TUFFC.2012.2165.
The piezoelectric ultrasonic composite transducer, which can be used in either gas or liquid media, is studied in this paper. The composite transducer is composed of a longitudinal sandwich piezoelectric transducer, a mechanical transformer, and a metal circular plate in flexural vibration. Acoustic radiation is produced by the flexural circular plate, which is excited by the longitudinal sandwich transducer and transformer. Based on the classic flexural theory of plates, the equivalent lumped parameters for a plate in axially symmetric flexural vibration with free boundary conditions are obtained. The radiation impedance of the plate is derived and the relationship between the radiation impedance and the frequency is analyzed. The equivalent circuits for the plate in flexural vibration and the composite transducer are given. The vibrational modes and the harmonic response of the composite piezoelectric transducer are simulated by the numerical method. Based on the theoretical and numerical analysis, two composite piezoelectric ultrasonic transducers are designed and manufactured, their admittance-frequency curves are measured, and the resonance frequency is obtained. The flexural vibrational displacement distribution of the transducer is measured with a laser scanning vibrometer. It is shown that the theoretical results are in good agreement with the measured resonance frequency and the displacement distribution.
本文研究了可用于气体或液体两种介质的压电超声复合换能器。复合换能器由纵向夹心式压电换能器、机械变压器和金属圆形弯曲振动板组成。弯曲圆形板通过纵向夹心换能器和变压器激励产生声辐射。基于板的经典弯曲理论，得到了具有自由边界条件的轴对称弯曲振动板的等效集总参数。推导了板的辐射阻抗，并分析了其与频率的关系。给出了弯曲振动板和复合换能器的等效电路。通过数值方法对复合压电超声换能器的振动模态和谐响应进行了模拟。基于理论和数值分析，设计并制造了两个复合压电超声换能器，测量了它们的导纳-频率曲线，并得到了共振频率。用激光扫描测振仪测量了换能器的弯曲振动位移分布。结果表明，理论结果与测量的共振频率和位移分布吻合较好。
